1. Field of the Invention
The present invention relates to a susceptor device which is used for fixing a plate sample such as a silicon wafer preferably in a semiconductor manufacturing device for manufacturing a semiconductor device such as an IC (Integrated Circuit), an LSI (Large Scale Integration), and a VLSI (Very Large-Scale Integration). In particular, the present invention relates to a susceptor device which fixes the plate sample by an electrostatic force while supporting the plate sample efficiently in a constant temperature so as to perform various operations such as a plasma-operation.
2. Description of Related Art
Conventionally, in manufacturing processes for manufacturing a semiconductor device such as an IC, an LSI, and a VLSI, the plate sample such as a silicon wafer is fixed on a sample mount which is called a susceptor body such that predetermined operations may be performed thereto.
For example, operations such as an etching operation are performed to the plate sample under a plasma atmosphere condition, temperature on a surface of the plate sample increase due to a heat which is caused in the plasma; thus, there may be a problem that a resist layer on the surface thereon may burst. For dealing with such a problem, a susceptor device has been proposed in which a temperature controlling section having a flow path for a medium for controlling the temperature of the medium thereinside is attached unitarily to a bottom surface of a susceptor base body on which the plate sample is fixed. A cooling medium is circulated in the flow path in the temperature controlling section so as to exchange a heat therein. Consequently, the plate sample is absorbed by an electrostatic force while the temperature of the plate sample is maintained at a preferable constant temperature such that various plasma operations may be performed to the plate sample.
FIG. 3 is a cross section for showing an example for such a susceptor device. Here, a susceptor device 1 comprises a ceramic mounting plate 2 of which upper surface 2a serves for mounting a plate sample thereon, a ceramic supporting plate 3 for supporting the mounting plate 2 from therebeneath, an electrostatic absorbing inner electrode 4 and a ring insulating member 5 which are disposed between the mounting plate 2 and the supporting plate 3, an electricity supplying terminal 7 which is disposed in a fixing hole 6 formed on the supporting plate 3 so as to contact the electrostatic absorbing inner electrode 4, and a temperature controlling section 8 which is disposed beneath the supporting plate 3 and has a flow path 8a thereinside for circulating a cooling medium. Here, the supporting plate 3 and the temperature controlling section 8 are attached unitarily via a bonding agent layer 9 which is formed by a bonding agent which contains a soft brazing member such as an Indium (In) or an Indium alloy. Also, an outer periphery of the electricity supplying terminal 7 is surrounded by an insulating member 10. The electricity supplying terminal 7 is connected to an external direct current power supply 11. A body of the temperature controlling section 8 is formed by a conductive member so as to serve as an inner electrode for generating a plasma compatibly so as to be connected to an external high frequency power supply 12.
However, in the conventional susceptor device 1 as explained above, thickness of a ceramic supporting plate 3 is at least 3 mm; therefore, a heat is not sufficiently efficiently exchanged between the plate sample and the temperature controlling section 8. Thus, there has been a problem in that it is difficult to maintain the plate sample at a constant preferable temperature. Thus, it has been desired that an operability for controlling the temperature in the conventional susceptor device 1 be improved further.
Also, in the susceptor device 1, the thickness of the supporting plate 3 is at least 3 mm; therefore, there has been a problem in that it is difficult to generate a plasma stably because there is not a sufficient transparency for the plasma.
Also, in the susceptor device 1, there has been a concern that a heavy metal component in a bonding agent layer 9 may be volatile because the bonding agent layer 9 is not durable enough to a corrosive gas and a plasma. Therefore, such a volatile heavy metal component may cause a contamination on the plate sample or become a source for generating a particle.
Furthermore, the bonding agent layer 9 is a conductive member; therefore, there has been a concern that there may occur an abnormal electric discharge on the bonding agent layer 9 when the bonding agent layer 9 is exposed to a plasma; thus there may occur a dielectric breakdown on the bonded surface. Therefore, there has been a problem in that the susceptor device 1 does not work stably due to a frequent interruption by a safety device and a susceptor device 1 is not durable enough even if the susceptor device 1 works stably.